1. Field of the Invention
The present invention relates to a current sensor with high precision and low power consumption over a wide measurement range.
2. Description of the Related Art
An example of a current measuring device that measures current over a wide measurement range is disclosed in Japanese Unexamined Patent Application Publication No. 2000-162248. In the current measuring device, two high and low shunt resistors are connected in series and a diode is connected in parallel to a high shunt RL of a resistor for measuring small current. In such a current measuring device, in a state where a potential difference is equal to or more than Vf (large current range), it is possible to reduce power consumption with the shunt RL as a bypass.
In the shunt resistor manner, when the measurement target current gets larger, power consumption gets higher in the current sensor, and the measurement range of the measurement target current gets narrower. In the current measuring device disclosed in Japanese Unexamined Patent Application Publication No. 2000-162248, the measurement range is widened using a plurality of shunt resistors, but in the large current range after the diode is turned on, the rated current in the shunt of the low resistor determines the upper limit of primary current, which is still a problem.